This invention relates to an interconnection device and method for securing a safety rail, and in particular, but not exclusively, to an interconnection device and a method for securing a safety rail to the frame of an access hatch such as a roof hatch.
In order to comply with safety regulations it is known to secure a safety rail structure to a rigid frame which defines a roof hatch opening such as is commonly provided in a flat roof. In one known and established technique of constructing a safety rail structure, vertical posts for forming part of a safety rail assembly are welded to brackets that in turn are bolted to the hatch frame. In general on site welding of the posts to the brackets is not convenient and, in the case of brackets pre secured to a roof hatch, on site welding creates an unacceptable risk of damage to the roofing material surrounding the hatch. It is therefore common practice to pre-weld the posts and brackets to one another, but that results in sub-assemblies of an inconvenient shape for storage and transportation.
One object of the present invention is to provide an improved interconnection device and method for securing a post of a safety rail assembly to a hatch structure.
In accordance with one aspect of the present invention a method of securing a safety rail structure to a hatch structure comprises providing an interconnection device comprising at least one flange portion adapted for attachment to a rigid frame of the hatch structure and a receiving portion for receiving a part of the safety rail structure, said receiving portion comprising locking means for selectively releasably securing thereto an end portion of an elongate member of the safety rail structure.
The method may comprise securing at least one said structural interconnection device to the frame of a hatch either prior to or subsequent to fitting the hatch frame to an opening in a roof or other surface and then securing to the or each structural interconnection device an end portion of an elongate member which forms a part of the safety rail structure. Preferably the end portion of an elongate member is selectively releasably secured to a structural interconnection device. The structural interconnection device may be provided with locking means operable to engage with the end portion of the elongate member and thereby secure that member to the interconnection device and hatch frame.
The method of the invention may comprise use of a structural interconnection device of a type as hereinafter more specifically disclosed.
In accordance with a further aspect of the present invention a structural interconnection device for attachment of an elongate member to a rigid frame comprises at least one flange portion adapted for attachment to the rigid frame, and a receiving portion comprising locking means for selectively releasably securing thereto an end portion of an elongate member, said flange portion having a location surface for bearing against said rigid frame and said location face lying, in use, in a plane which is substantially parallel with a longitudinal axis of an end portion of the elongate member secured to said receiving portion and said plane of the location face lying, in use, in a plane displaced from said longitudinal axis of the end portion of the elongate member.
Preferably the flange and receiving portions are integrally formed. They may, for example, be integrally formed from cast iron, steel or aluminium.
The receiving portion may comprise a tubular shaped formation into which the end portion of an elongate member may be received. Said receiving portion may comprise a bore of circular or, for example, square cross-section. The bore may be of uniform dimension along its length, or it may be formed with axially spaced ribs that extend inwards and provide bearing surface regions for contact by the end portion of the elongate member.
The locking means may, for example, comprise at least one screw threaded aperture formed in a wall portion of the receiving portion and into which a grub screw or like member may be received and rotated to bear at an inner end against the surface of an end portion of an elongate member. If the bore of the receiving portion comprises at least one pair of axially spaced ribs, preferably a screw threaded aperture is provided at an axial position between the or each successive pair of ribs. One end of the bore may comprise an inwardly extending projection to act as a limit stop abutment against which an end of an elongate member may abut. Said abutment formation may be provided with a central aperture thereby to allow for drainage. Preferably that end of the receiving portion formed with an abutment is aligned with any edge (in use a lower edge) of the or each flange portion. The other end of the receiving portion may extend beyond the other, in use upper, edge of the or each flange portion.
The interconnection device may comprise a single flange portion and location surface for bearing against a rigid frame. In that case preferably a screw threaded aperture or like locking means of the receiving portion lies at a region of the receiving portion furthest from said location surface.
The interconnection device may comprise two flange portions the respective location surfaces of which lie in planes perpendicular to one another and each displaced from but parallel with a longitudinal axis of a bore defined by the receiving portion. A screw threaded aperture or like locking means of the receiving portion may lie in a plane which contains the longitudinal axis of a bore of the receiving portion and which intersects the angle defined between two location surfaces. In the case of an interconnection device comprising two flange portions, the location surface of each flange portion may be spaced from the receiving portion by an intermediate section. Preferably said intermediate sections of the two associated with the two flange portions are spaced apart thereby to provide a space which, in use, may be occupied by roofing material e.g. where roofing material of sheet form has been folded in the vicinity of a corner of a hatch frame.
The present invention further provides a safety rail system for an access hatch and comprising as discreet and interconnectable components elongate post members for extending vertically in use, elongate rail members for extending substantially horizontally in use, connectors for interconnecting the posts and rails, and structural interconnection devices to which ends of the posts may be secured, said interconnection devices being of a kind in accordance with the present invention and each comprising at least one flange surface for securing to the frame of a hatch structure.
Embodiments of the present invention will now be described, by way of example only, with reference to the accompanying diagrammatic drawings in which: